Methanol synthesis system using co 2-rich syngas
Patent Information
- Application Number
- PCT/CN2025/116855
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-12
- Filing Date
- 2025-08-26
- Publication Date
- 2026-09-17
Smart Images
Figure CN2025116855_17092026_PF_FP_ABST
Abstract
Description
A CO2-rich syngas methanol synthesis system Technical Field
[0001] This invention relates to a CO2-rich syngas methanol synthesis system, belonging to the field of green methanol preparation technology. Background Technology
[0002] Methanol, characterized by high combustion efficiency, clean emissions, and renewability, is hailed as a new type of clean energy, often referred to as "liquid sunshine." In marine applications, existing vessels can be adapted to use methanol as fuel with only minor modifications, effectively saving investment costs. Compared to liquefied natural gas (LNG), which requires cryogenic liquefaction, methanol is liquid at room temperature, making it easier to store, transport, and use. In the future, methanol will replace traditional high-carbon marine fuels and see widespread application. Against the backdrop of global carbon reduction and carbon neutrality, shipping giants have formulated plans to replace fuel oil with green methanol as a marine fuel to achieve carbon reduction. The demand for green methanol in the shipping industry will grow rapidly in the future, and the industry of producing green methanol using clean and renewable energy will also enter a period of rapid development.
[0003] Biomass gasification coupled with green hydrogen production to produce chemical products such as methanol and green aviation kerosene is an important pathway for the clean development of chemical fuels. Biomass, as a renewable resource, is characterized by abundant resources, wide geographical distribution, and stable energy reserves. Syngas produced from biomass gasification, after adjusting the hydrogen-to-carbon ratio through a shift conversion system, can be used alone as a feedstock for methanol synthesis. However, the shift conversion system requires additional steam consumption and emits some CO2, leading to a decrease in the utilization rate of renewable carbon sources. With the increase in my country's renewable energy power generation capacity, the unstable output of renewable energy has resulted in a serious problem of "wind and solar curtailment." The curtailment of new energy power generation is becoming increasingly prominent, hindering the development and utilization of new energy sources. Utilizing renewable energy power generation (such as wind and solar) for water electrolysis to produce hydrogen, and then combining this hydrogen with biomass syngas to synthesize methanol, is one effective way to solve the problem of new energy power curtailment. It can also improve the utilization rate of CO2 in biomass syngas and reduce methanol production costs.
[0004] In summary, there is an urgent need for a CO2-rich syngas methanol synthesis system to solve the problems of low renewable carbon (CO2) utilization rate in biomass gasification for green methanol production and the system adaptability issues of biomass gasification coupled with fluctuating green hydrogen for green methanol synthesis. Summary of the Invention
[0005] Currently, large-scale hydrogen production through water electrolysis primarily relies on hydrogen generated from new energy sources (wind power and solar power). Due to the high volatility and randomness of new energy power generation, the hydrogen produced through water electrolysis also exhibits significant volatility. When this highly volatile hydrogen is used as a feedstock for green methanol synthesis, it places higher demands on the adaptability of the methanol synthesis system. Furthermore, green methanol requires renewable carbon sources, such as carbon from biomass. Current traditional methanol synthesis technologies have low carbon utilization efficiency; renewable carbon is a valuable resource that needs to be utilized as efficiently as possible.
[0006] The technical problem to be solved by this invention is the low utilization rate of renewable carbon (CO2) in biomass gasification to produce green methanol and the system adaptability problem of biomass gasification coupled with fluctuating green hydrogen to synthesize green methanol.
[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is to provide a CO2-rich synthesis gas methanol synthesis system, the technical solution being as follows:
[0008] The system includes: a hydrogen storage unit, a syngas decarbonization unit, a syngas compression unit, a synthesis unit, a gas / gas heat exchanger, a cooler, a high-pressure flash evaporator, a hydrogen recovery unit, a low-pressure flash evaporator, and a low-pressure flash vapor compression unit;
[0009] The hydrogen storage unit can receive fluctuating hydrogen supply and hydrogen recovered by the hydrogen recovery unit. After being buffered by the hydrogen storage unit, relatively stable hydrogen is formed, which together with CO2-rich syngas is used as the feed gas for methanol synthesis. The CO2-rich syngas is formed by mixing syngas generated by the syngas decarbonization unit and low-pressure flash vapor obtained from the low-pressure flash evaporator. After the hydrogen and CO2-rich syngas are mixed, they enter the methanol synthesis loop. The hydrogen in the purge gas is returned to the hydrogen storage unit for continued use, and the flash vapor from the low-pressure flash evaporator is also returned to the methanol synthesis loop for continued use.
[0010] Preferably, the hydrogen storage unit is a gaseous hydrogen storage unit with a storage pressure of 1.0 MPa to 8.0 MPa;
[0011] Preferably, the syngas decarbonization unit can achieve different CO2 removal rates as needed, thereby giving the syngas (202) a wide range of CO2 concentrations, wherein the CO2 concentration is 3 mol% to 50 mol%.
[0012] Preferably, the flash pressure of the low-pressure flash evaporator is 0.1 MPa to 1.0 MPa; the low-pressure flash vapor is pressurized by the low-pressure flash vapor compression unit and then returned to the methanol synthesis system to continue synthesizing methanol.
[0013] Preferably, the operating pressure of the hydrogen recovery unit is 0.3 MPa higher than that of the hydrogen storage unit, and the recovered hydrogen is sent to the hydrogen storage unit.
[0014] Preferably, the methanol synthesis circuit is composed of a synthesis gas compression unit, a synthesis unit, a gas / gas heat exchanger, a cooler (600), and a high-pressure flash evaporator, and the operating pressure of the synthesis circuit is 5MPa to 10MPa.
[0015] This invention adapts to the fluctuations in green hydrogen supply by adjusting the CO2 content in the feed gas. When the green hydrogen supply is at its peak, the CO2 removal rate of the syngas decarbonization unit is reduced, increasing the CO2 content in the syngas entering the methanol synthesis loop. The excess hydrogen reacts with the CO and a large amount of CO2 in the syngas to produce green methanol. When the green hydrogen supply is at its lowest, the CO2 removal rate of the syngas decarbonization unit is increased, reducing the CO2 content in the syngas entering the methanol synthesis loop. The appropriate amount of hydrogen reacts with the CO and a small amount of CO2 in the syngas to produce green methanol.
[0016] This invention provides a CO2-rich syngas methanol synthesis system, realizing the production of green methanol from high-concentration CO2 syngas coupled with fluctuating green hydrogen supply. The system of this invention is stable and reliable in operation, has high renewable carbon (CO2) utilization, and can adapt to fluctuating hydrogen supply. Compared with existing technologies, this invention has the following advantages:
[0017] (1) The present invention uses fluctuating green hydrogen supply to adjust the hydrogen-carbon ratio in the methanol synthesis feed gas, and eliminates the instability of fluctuating green hydrogen by setting up a hydrogen storage unit, thereby achieving stable operation of methanol synthesis.
[0018] (2) Compared with conventional methanol synthesis systems, the present invention can convert a large amount of CO2 into methanol, thereby improving the utilization rate of renewable carbon (CO2). Attached Figure Description
[0019] Figure 1 is a schematic diagram of a CO2-rich syngas methanol synthesis system provided by the present invention. 101 - Fluctuating hydrogen supply; 100 - Hydrogen storage unit; 102 - Hydrogen; 200 - Syngas decarbonization unit; 201 - Biomass syngas; 202 / 203 - CO2-rich syngas; 204 - CO2 gas; 300 - Syngas compression unit; 301 / 501 - Methanol synthesis feed gas; 400 - Methanol synthesis unit; 401 / 502 - Methanol synthesis discharge gas; 500 - Gas / gas heat exchanger; 600 - Methanol cooler; 601 - Methanol mixture; 700 - High-pressure flash evaporator; 701 - High-pressure flash vapor; 702 - Circulating gas; 703 - Hydrogen recovery feed gas; 800 - Hydrogen recovery unit; 801 - Hydrogen; 802 - Purge gas; 704 / 901 - Crude methanol; 900 - Low-pressure flash evaporator; 902 / 1002 - Low-pressure flash vapor; 1000 - Low-pressure flash vapor compression unit. Detailed Implementation
[0020] The present invention will be further described below with reference to specific embodiments.
[0021] Example: The purpose of this invention is to maximize the utilization of renewable carbon in biomass while simultaneously addressing the system adaptability challenges of biomass gasification coupled with fluctuating green hydrogen to synthesize green methanol. To achieve the above objectives, this invention provides a CO2-rich syngas methanol synthesis system. To further clarify this invention, a specific embodiment with a green methanol production capacity of 100,000 tons / year will be described. As shown in Figure 1, a CO2-rich syngas methanol synthesis system mainly includes a hydrogen storage unit, a syngas decarbonization unit, a syngas compression unit, a synthesis unit, a gas / gas heat exchanger, a cooler, a high-pressure flash evaporator, a hydrogen recovery unit, a low-pressure flash evaporator, and a low-pressure flash vapor compression unit.
[0022] Designed for 8000 hours of operation per year, the methanol production capacity is approximately 13 t / h. The hydrogen (102) supply pressure is 1.5 MPa, and the normal flow rate is 8000 Nm³. 3 / h, flow rate variation range is 1000 Nm 3 / h~17600Nm 3 / h. The hydrogen storage unit (100) has a hydrogen storage pressure of 1.4 MPa and a hydrogen storage capacity of 200,000 Nm³. 3 The pressure of the biomass syngas (201) is 0.3 MPa, and the normal composition of the syngas is CO 25 mol%, CO2 30 mol%, H2 35 mol%, and other components 10 mol%. The normal flow rate is 34000 Nm³. 3 / h, with a flow rate variation range of 13600Nm 3 / h~34000Nm 3 / h; After passing through the decarbonization unit (200), the CO2 content of the syngas varies from 2.6 mol% to 30 mol%. From the above parameters of the feed gas, it can be seen that the hydrogen flow rate varies from 12.5% to 220% of the normal flow rate, and the syngas flow rate varies from 40% to 100% of the normal flow rate. To accommodate these fluctuations, this invention includes a dedicated methanol synthesis catalyst, which is packed in the methanol synthesis unit (400). Simultaneously, to adapt to load changes, this invention also includes a dedicated methanol synthesis reactor, capable of operating at pressures ranging from 5 MPa to 10 MPa.
[0023] This invention needs to switch between different operating conditions. The operating conditions are shown in Table 1 and are described below.
[0024] Table 1 shows the operating condition parameters.
[0025] Operating Condition 1: When the hydrogen supply flow rate is 17600 Nm 3At a rate of / h, if the hydrogen storage unit is at full capacity, then at 26600 Nm 3 Hydrogen gas is fed directly into the methanol synthesis loop at a rate of 1 h until the hydrogen storage tank reaches its minimum level. The entire process can last for about 18 hours. This process does not require the removal of CO2 from the biomass syngas. The methanol synthesis loop operates at the upper limit of the operating pressure, and the carbon source (CO / CO2) can be utilized efficiently.
[0026] Operating conditions 2-4: When the hydrogen supply flow rate is 17600 Nm 3 If the hydrogen storage unit is at full capacity at a rate of / h, but a decrease in hydrogen supply is anticipated, then the rate will be 10600 Nm³ / h. 3 / h~22000Nm 3 Hydrogen gas is fed directly into the methanol synthesis loop at a rate of / h until the hydrogen storage tank is reduced to a minimum. This process requires reducing the synthesis gas supply load to save on raw material consumption. The methanol synthesis loop is at the upper limit of the operating pressure, and there is still no need to remove CO2 from the biomass synthesis gas. The carbon source (CO / CO2) can be utilized efficiently.
[0027] Operating Condition 5: When the hydrogen supply flow rate is 8000 Nm 3 At a rate of / h, if the hydrogen storage unit is at full capacity, then at 11000 Nm 3 Hydrogen gas is fed directly into the methanol synthesis loop at a rate of / h until the hydrogen storage tank is reduced to a minimum. The entire process can last for about 80 hours. This process requires reducing the synthesis gas supply to a minimum load. The methanol synthesis loop is at the middle value of the operating pressure. There is no need to remove CO2 from the biomass synthesis gas. The carbon source (CO / CO2) can be used efficiently.
[0028] Operating conditions 6-8: When the hydrogen supply flow rate is 8000 Nm³ 3 At / h, it is determined whether the syngas supply load needs to be increased based on the annual methanol production demand. If so, the syngas supply load is gradually increased to increase methanol production. The methanol synthesis loop is at the middle value of the operating pressure. At the same time, some CO2 needs to be removed from the syngas, and the utilization rate of carbon source (CO2) is reduced.
[0029] Operating conditions 9-10: When the hydrogen supply flow rate is below 4000 Nm 3 When the pressure is reduced to 40%, the syngas supply load needs to be reduced to 40%, and most of the CO2 in the syngas needs to be removed. The methanol synthesis loop is at the lower limit of the operating pressure, and the utilization rate of the source (CO2) is further reduced.
[0030] The above-described operating conditions are merely limited examples for understanding this invention. Based on the hydrogen storage capacity of the hydrogen storage unit and the predicted changes in hydrogen supply, different combinations can be made of several key indicators, such as the hydrogen flow rate out of the storage tank, the syngas supply load, the CO2 removal rate, and the operating pressure of the methanol synthesis loop, to achieve the annual production target.
[0031] As can be seen from the above embodiments, this invention, through innovative system design and reasonable process parameter setting, uses hydrogen generated from new energy power generation to adjust the hydrogen-to-carbon ratio in the methanol synthesis feedstock gas, and provides relatively stable green hydrogen to the synthesis unit by setting up a hydrogen storage unit; by setting up a synthesis gas purification unit with adjustable CO2 removal rate, it achieves relatively stable operation of biomass synthesis gas coupled with green hydrogen to produce green methanol; by using a dedicated methanol synthesis catalyst and reactor, it achieves efficient CO2 utilization and highly flexible methanol synthesis operation, efficiently utilizes renewable carbon and hydrogen sources, and reduces the cost of green methanol production.
[0032] The above embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
Claims
A CO2-rich syngas methanol synthesis system, characterized in that, include: Hydrogen storage unit (100), syngas decarbonization unit (200), syngas compression unit (300), synthesis unit (400), gas / gas heat exchanger (500), cooler (600), high-pressure flash evaporator (700), hydrogen recovery unit (800), low-pressure flash evaporator (900), low-pressure flash vapor compression unit (1000); The hydrogen storage unit (100) can receive fluctuating supply of hydrogen (101) and hydrogen (801) recovered by the hydrogen recovery unit (800). After being buffered by the hydrogen storage unit (100), relatively stable hydrogen (102) is formed and used together with CO2-rich syngas (203) as raw material gas for methanol synthesis. The CO2-rich syngas (203) is formed by mixing the syngas (202) generated by the syngas decarbonization unit (200) and the low-pressure flash vapor (902) obtained by the low-pressure flash evaporator (900) after being pressurized by the low-pressure flash vapor compression unit (1000). After the hydrogen (102) and CO2-rich syngas (203) are mixed, they enter the methanol synthesis loop. A CO2-rich syngas methanol synthesis system as described in claim 1, characterized in that: The hydrogen storage unit (100) is for gaseous hydrogen storage, with a storage pressure of 1.0 MPa to 8.0 MPa. A CO2-rich syngas methanol synthesis system as described in claim 2, characterized in that: The hydrogen storage pressure is 1.5 MPa to 3 MPa. A CO2-rich syngas methanol synthesis system as described in claim 1, characterized in that: The syngas decarbonization unit (200) can achieve different CO2 removal rates as needed, thereby giving the syngas (202) a wide range of CO2 concentrations, from 1 mol% to 50 mol%. A CO2-rich syngas methanol synthesis system as described in claim 4, characterized in that: The CO2 concentration is 2 mol% to 30 mol%. A CO2-rich syngas methanol synthesis system as described in claim 1, characterized in that: The flash pressure of the low-pressure flash evaporator (900) is 0.1 MPa to 1.0 MPa; the low-pressure flash vapor (902) is pressurized by the low-pressure flash vapor compression unit (1000) and then returned to the methanol synthesis system to continue the synthesis of methanol. A CO2-rich syngas methanol synthesis system as described in claim 6, characterized in that: The flash pressure of the low-pressure flash evaporator (900) is 0.3MPa to 0.5MPa. A CO2-rich syngas methanol synthesis system as described in claim 1, characterized in that: The operating pressure of the hydrogen recovery unit (800) is 0.3 MPa higher than that of the hydrogen storage unit (100), and the recovered hydrogen (801) is sent to the hydrogen storage unit (100). A CO2-rich syngas methanol synthesis system as described in claim 1, characterized in that: The methanol synthesis circuit consists of a synthesis gas compression unit (300), a synthesis unit (400), a gas / gas heat exchanger (500), a cooler (600), and a high-pressure flash evaporator (700). The operating pressure of the synthesis circuit is 4MPa to 12MPa. A CO2-rich syngas methanol synthesis system as described in claim 1, characterized in that: The operating pressure of the synthesis circuit is 5MPa to 10MPa.